MANCHESTER, N.H. — Vying for the support of New Hampshire voters, several Republican presidential contenders threatened Thursday to skip the Nevada caucuses if the state GOP sticks with jumping the line by moving its contest into early January.

Former Utah Gov. Jon Huntsman Jr. struck first, vowing to boycott the Nevada caucuses if they fall on Jan. 14 — a move that puts it within 11 days of the Iowa caucuses that kick off the nomination process. The decision has New Hampshire officials seriously contemplating holding their primary as early as Dec. 6 — less than two months away.

“To jump ahead as they are, which kind of upends the traditional primary schedule is unfortunate, and I think is a disservice to the votes of this country,” Mr. Huntsman told The Washington Times after an appearance here at St. Anselm College.

Earlier in the day, the Huntsman campaign, which has focused its efforts heavily on this state’s first-in-the-nation primary, called on all the other candidates to join the effort, singling out Mitt Romney. Huntsman supporters even suggested that the former Massachusetts governor lobbied Nevada officials to push up the voting date.

The Romney camp refused to support the boycott, though his New Hampshire adviser, Jim Merrill, said the governor “is unequivocally committed to New Hampshire hosting the first primary contest during the 2012 cycle and beyond.”

“Governor Romney will compete in every nominating contest across the country, regardless of when they may be scheduled, so long as New Hampshire retains its first-in-the-nation primary status,” Mr. Merrill said.

By the end of the day, former House Speaker Newt Gingrich and former Sen. Rick Santorum of Pennsylvania voiced support for Mr. Huntsman’s effort.

Rep. Ron Paul of Texas said he also supported New Hampshire’s right to go first but said threats of punishing other states was not helping the party.

“This talk of boycotts doesn’t serve the electoral process any more than the states’ jockeying for position and primacy. New Hampshire deserves its rightful place as the first primary in the nation, but we will fight to preserve that place without depriving Nevada or Iowa voters of their say in the 2012 nomination process,” Paul campaign chairman Jesse Benton said in a statement.

While some suggest Mr. Romney’s GOP rivals were simply trying to chip away at his top-tier status, the responses are the latest sign that Republican Party hopes for an orderly primary process to choose its presidential nominee are on the rocks, as state parties have rushed to cut in line and poach some of the influence long enjoyed by New Hampshire, Iowa, South Carolina and other early-voting states.

New Hampshire Secretary of State William Gardner drew a line in the sand on Thursday, warning in an interview with The Times that state law — and his personal commitment for historical precedent -requires that he protect New Hampshire’s position, even if that means holding the vote three weeks before Christmas.

Mr. Gardner has full authority to set the state’s primary date — something he said he has done eight times since 1976. On Wednesday, he made headlines by floating the possibility of New Hampshire pushing its primary to Dec. 13 or Dec. 6 in response to Nevada’s move.

“I’m only asking Nevada to go 72 hours back,” he said during the interview into his office on Thursday. “If we have to have the primary before the end of the year, we will, to preserve and honor the tradition of the New Hampshire first-in-the-nation presidential primary and to comply with state law.”

New Hampshire House Speaker Bill O’Brien, meanwhile, called for a boycott and told The Times that he hopes Nevada will show some flexibility, so all the nominating contests can be held not earlier than January.

“Barring that, I think its going to be difficult for New Hampshire to keeps its primary in January,” Mr. O’Brien said, adding that the front-loaded schedule will rob the candidates of the opportunity to hone their campaign message in the retail politicking needed to win in the Granite State. “Front-loading it, to the beginning of January or beginning of December is not positive at all.”